Thermoelectric elements that use thermoelectric semiconductor elements made of compounds such as bismuth/tellurium compounds, iron/silicon compounds, or cobalt/antimony compounds are used in applications such as cooling/heating devices. Such a thermoelectric element is convenient as a cooling/heating source that does not use liquids or gases, takes up little space, is not subject to rotational friction, and does not require maintenance.
The structure of a thermoelectric module that is known in the prior art is shown in FIGS. 11A and 11B. In this case, FIG. 11A is a front view and FIG. 11B is a perspective view. As shown in these figures, thermoelectric semiconductor elements 33 consisting of n-type thermoelectric semiconductor elements and p-type thermoelectric semiconductor elements are arrayed alternately, and upper and lower surfaces of the thermoelectric semiconductor elements 33 are connected to metal electrodes 32 and metal electrodes 34, respectively. The thermoelectric semiconductor elements 33 are connected alternately by the upper and lower surfaces thereof to the metal electrodes 32 and the metal electrodes 34, so that all of the thermoelectric semiconductor elements 33 are eventually connected electrically in series. The connections between the upper and lower metal electrodes 32 and 34 and the thermoelectric semiconductor elements 33 are performed by soldering. The metal electrodes 32 and 34 at these upper and lower surfaces are connected onto metallized ceramic substrates 31 and 33, respectively, to fix the entire assembly together.
A DC power source is connected to the electrodes of this thermoelectric module. When a current flows in the direction from each n-type thermoelectric semiconductor element to a p-type thermoelectric semiconductor element, the Peltier effect ensures that heat is absorbed by the upper portion of each .pi. shape and heat is emitted from the lower portion thereof. In other words, each .pi.-shaped upper portion acts as an absorbing-side cold junction (CJ) and each lower portion thereof acts as a radiating-side hot junction (HJ) as shown in FIG. 11A. Reversing the connection direction of the power source changes the directions in which heat is absorbed and emitted. This phenomenon is utilized so that the thermoelectric element can be used in a cooling/heating device. Such a thermoelectric module is useful in a wide range of applications, from the cooling of devices such as large-scale integrated circuits (LSIs), computer central processing units (CPUs), and lasers, to use in insulated refrigerators.
If such a thermoelectric module is used as a cooling device, it is necessary to disperse heat efficiently from the heat-radiating side. Methods that are used in the art for dispersing heat from the heat-radiating side of a thermoelectric module include an air-cooling method wherein radiator fins 41 are attached to the heat-radiating side of the thermoelectric module and wind from a fan 42 is directed towards these radiator fins 41, as shown in FIG. 12A, and a liquid-cooling method wherein a liquid-cooling jacket 51 is attached to the heat-radiating side of the thermoelectric module and a coolant passes from a liquid inlet 52 of this liquid-cooling jacket 51 to a liquid outlet 53 thereof, as shown in FIG. 12B. Note that the hollow arrows in FIG. 12A indicate the flow of air and the solid arrows in FIG. 12B indicate the flow of coolant. In both FIGS. 12A and 12B, CL denotes a cooling load.
However, since the thermoelectric semiconductor elements in each of these cooling devices are cooled indirectly through a ceramic substrate on the lower sides thereof, the heat cannot be dispersed efficiently from the heat-radiating side of the thermoelectric module. In addition, the ceramic substrates that are fixed above and below the thermoelectric module of FIG. 11 form a rigid structure, so that large thermal stresses are inevitably applied to the thermoelectric semiconductor elements during operation, and thus the lifetime of these thermoelectric semiconductor elements is short.
The present inventors have already proposed a thermoelectric module, together with a thermoelectric cooling unit that uses this thermoelectric module, in which thermal stresses on the thermoelectric semiconductor element are alleviated by directly cooling the heat-radiating side of the thermoelectric semiconductor elements and the metal electrodes that are connected thereto, to disperse heat efficiently from the heat-radiating side, and also by making the structure a double-sided skeleton structure (Japanese Patent Application No. 8-354136).
In the previously proposed thermoelectric cooling unit, the heat-radiating side of the thermoelectric semiconductor elements and the metal electrodes connected thereto are cooled directly, so that heat can be efficiently dispersed from the heat-radiating side and thus the capabilities of the thermoelectric semiconductor element can be fully utilized. Since the thermal stresses applied to the thermoelectric semiconductor elements are alleviated, a longer lifetime is achieved for the thermoelectric semiconductor elements.
An objective of this invention is to provide a thermoelectric module unit using a thermoelectric module of a double-sided skeleton structure, which enables an improvement in the heat-dispersion efficiency.